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Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

Adding fibers into cement to form fiber-reinforced soil cement material can effectively enhance its physical and mechanical properties. In order to investigate the effect of fiber type and dosage on the strength of fiber-reinforced soil cement, polypropylene fibers (PPFs), polyvinyl alcohol fibers (PVAFs), and glass fibers (GFs) were blended according to the mass fraction of the mixture of cement and dry soil (0.5%, 1%, 1.5%, and 2%). Unconfined compressive strength tests, split tensile strength tests, scanning electron microscopy (SEM) tests, and mercury intrusion porosimetry (MIP) pore structure analysis tests were conducted. The results indicated that the unconfined compressive strength of the three types of fiber-reinforced soil cement peaked at a fiber dosage of 0.5%, registering 26.72 MPa, 27.49 MPa, and 27.67 MPa, respectively. The split tensile strength of all three fiber-reinforced soil cement variants reached their maximum at a 1.5% fiber dosage, recording 2.29 MPa, 2.34 MPa, and 2.27 MPa, respectively. The predominant pore sizes in all three fiber-reinforced soil cement specimens ranged from 10 nm to 100 nm. Furthermore, analysis from the perspective of energy evolution revealed that a moderate fiber dosage can minimize energy loss. This paper demonstrates that the unconfined compressive strength test, split tensile strength test, scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) pore structure analysis offer theoretical underpinnings for the utilization of fiber-reinforced soil cement in helical pile core stiffening and broader engineering applications.

Understanding effect of freezing phenomenon in a fiber-reinforced soil structure is essential to foundation technology, road construction and earthwork application in cold region. This research aims to present the results of experimental investigation relative to the unconsolidated-undrained triaxial compression behavior of fine-grained soil as a function of freeze-thaw cycles and fiber volume fractions. All measurements were carried out for 3 selected glass and basalt fiber fractions (0%, 0.5%, and 1%) and 5 selected freeze-thaw cycles (0, 2, 5, 10, and 15). It has been observed that for the studied soil, strength of unreinforced soil reduced with increasing number of the freeze-thaw cycles while fiber-reinforced soil shows greater effect and the strength reduction amount reduces from 40% to 18%. Moreover, the reduction trend for cohesion of the fiber-reinforced soil decreased, this was seen more prevalent on 1% glass fiber-reinforced soil. The resilient modulus of all specimens reduced with increasing number of the freezethaw cycles. The experimental results demonstrated that different fiber fractions and their mixtures could be employed as supplement additive to improve the freeze-thaw performance of cohesive soils for road construction and earthworks.

This paper presents a new design numerical tool for geosynthetic-reinforced soil embankments, used to mitigate rockfall risk in scenarios of large volumes, energies, and multiple block failures. The model can simulate both local block penetration into the uphill embankment face and extrusion mechanism frequently affecting the downhill face. The new model is based on an existing elastic-visco-plastic model, originally developed to simulate impacts of blocks on homogeneous granular strata. The model has been enhanced and modified by incorporating a plastic mechanism, accounting for the extrusion process potentially occurring within the embankment body. The model is initially described and then validated using available in situ real-scale test data; finally, the results of a parametric study, examining the influence of the main controlling parameters and the applicability of the tool for pre-design purposes, are illustrated. Highlights A new model simulating the mechanical response of a reinforced-soil embankment impacted by a rigid block is introduced. The model quantitatively reproduces both local and global interaction mechanisms occurring at impact. Both geometric and kinematic parameters affecting the reinforced embankment response are investigated. Model capabilities are demonstrated against experimental results and empirical formulas.

To research the unconsolidated undrained shear strength and deformation properties of saturated cotton fiber reinforced soil, the shear strength of saturated fiber reinforced soil is studied through a series of unconsolidated undrained shear tests. The test results show that the stress–strain relationship of the fiber reinforced soil is strain hardening, and the failure mode of the samples is bulging failure. Tensile properties of fibers require a certain strain to be “mobilized”. When the strain is less, the fiber content and the fiber length have less influence on the principal stress difference, and the reinforcement effect is weak. The reinforcement effect enhances with the increasing of axial strain. The unconsolidated undrained shear strength of saturated fiber reinforced soil increases first and then decreases with the increasing of fiber content and fiber length. The strength is the best under the condition of 1.0% fiber content and 3.09 cm fiber length, and the strength of fiber reinforced soil increases by 63.5% compared with that of unreinforced soil. Fiber reinforcement can weaken the end effect of the samples, and effectively constrain the radial deformation of the soil. By analyzing the interaction modes between the fibers and the soil particles, it is found that the interaction modes are contact, bending and interweaving. These three actions provide the interfacial shear stress between the fibers and the soil particles, and the tensile stress of fibers to restrict the movement of soil particles, and the interactions improve the shear strength of soil.

The Geosynthetic Reinforced Soil-Integrated Bridge System (i.e. GRS-IBS) was developed to address the bumping issue from differential settlement at bridge abutments. This study focused on a Louisiana bridge abutment, using numerical simulation with the finite difference method to assess deformation and stress under dynamic loads. Results showed that deformation of the soil abutment and geogrid increased with the vehicle weight, with a more pronounced effect on lateral displacement than settlement. Settlement values initially decreased then rose with speeds between 30 and 60 km/h, mirroring the trend in lateral displacement and geogrid deformation. The lateral displacement of the geogrid was roughly half that of the panel. Shear stress on the abutment at 5 tons was double that at 1.75 tons, and geogrid stress was triple. Analysis indicated that a vehicle speed of around 45 km/h had the least impact on the reinforced soil abutment. The findings offer valuable insights for the use and maintenance of reinforced earth bridge abutments.

Geosynthetics are human made material used to reinforce soils to improve the bearing capacity and permeability of the soil, reducing soil settlement. Geosynthetics application plays a vital role in the highways constructions with no additive layers, such as cement concrete, asphalt concrete, or in a subgrade layer that affects the bearing capacity of unbounded layers. This paper presents the geosynthetics as a tensional material that has been used for reinforcement of clayey soil. Laboratory California bearing ratio (CBR) test samples were prepared with clayey soils. Clayey soil containing unreinforced soil and reinforced soil. The sample comprised thermally bonded nonwoven geotextiles (NW) and superior needle-punched nonwoven geotextiles (SNW) with different characteristics (NW 8, 10, 21, 30 and SNW 14, 25, 62, 75) with three-layered, based on the sample materials to perform defined tests. These tests show that, bearing ratio of reinforced soils with thermally bonded nonwoven geotextiles increases.

This study introduces a novel application of gene expression programming (GEP) for the reliability analysis (RA) of reinforced soil foundations (RSFs) based on settlement criteria, addressing a critical gap in sustainable construction practices. Based on the principles of probability and statistics, the soil uncertainties were mapped using the first-order second-moment (FOSM) approach. The historical data generated via a parametric study on a validated finite element numerical model were used to train and validate the GEP models. Among the ten developed GEP frameworks, the best-performing model, abbreviated as GEP-M9 (R2 = 0.961 and RMSE = 0.049), in the testing phase was used to perform the RA of an RSF. This model’s effectiveness in RA was affirmed through a comprehensive evaluation, including parametric sensitivity analysis and validation against two independent case studies. The reliability index (β) and probability of failure (Pf) were determined across various coefficient of variation (COV) configurations, underscoring the model’s potential in civil engineering risk analysis. The newly developed GEP model has shown considerable potential for analyzing civil engineering construction risk, as shown by the experimental results of varying settlement values.

Rainfall is recognised as one of the major external factors affecting the stability of retaining walls. The magnitude of rainfall directly influences the overall stability of retaining walls, while rainfall patterns alter the infiltration process and the saturation state of the soil, thereby affecting soil shear strength and retaining wall stability. In order to investigate the effects of rainfall pattern and intensity on the stability of reinforced soil gabion retaining walls, numerical simulations were carried out to examine wall stability under two typical rainfall patterns (uniform and intermittent) and three rainfall intensities (20 mm/d, 50 mm/d, and 80 mm/d). The results indicate that: (1) under uniform rainfall conditions, the extent of the soil pore water pressure response zone is greater than that under intermittent rainfall of the same intensity, and as the uniform rainfall intensity increases from 20 mm/d to 80 mm/d, the pore water pressure response zone expands by approximately four times; (2) the rainfall pattern exerts a certain influence on the distribution characteristics of the time-history curves of lateral displacement of the retaining wall, with the horizontal displacement under intermittent rainfall exhibiting a non-uniform growth pattern associated with the rainfall pattern; (3) uniform heavy rainfall has a more pronounced effect on the horizontal displacement of reinforced soil gabion retaining walls, with the maximum absolute horizontal displacement reaching approximately 12.89 mm; and (4) rainfall pattern affects the evolution of the slope stability coefficient, which gradually decreases and eventually stabilises under uniform rainfall, whereas under intermittent rainfall it shows a continuous decreasing trend characterised by alternating rates of reduction, with a greater reduction observed under uniform rainfall conditions. These findings elucidate the influence of different rainfall patterns and intensities on the displacement behaviour and stability of reinforced soil gabion retaining walls, and provide a reference for risk assessment of reinforced soil gabion retaining walls.

In the present study, an analytical model, based on the limit equilibrium method, was developed to evaluate the ultimate bearing capacity of strip footing resting on soil mass encapsulated with geosynthetic reinforcement. The failure mechanism of the encapsulated soil mass was proposed based on literature studies. Additionally, a 3D finite element model was created using hardening constitutive law to analyze the load-settlement behavior of the strip footing, the strain profile of the reinforced soil mass, and the mobilized tension of the encapsulated reinforcement layers. In the numerical study, the ratio l / B was varied while u / B and h / B were kept constant. The results from the analytical model were compared with those from the developed finite element model and both were further validated with published literature data, showing good agreement. The numerical studies identified the optimal reinforcement configuration of the encapsulated soil mass at l / B = 2, u / B = 0.3, and h / B = 0.6. The study demonstrated that the encapsulated soil mass provides an 11–12% increase in ultimate bearing capacity over the traditional horizontal reinforcing method. Graphical Abstract Graphical abstract of the present study